Species• There are over 360 species of sharks!

• They can range in size from small enough to fit in your hand to up to 46 feet!!

• Smallest Shark is the Pygmy Shark

• Largest Shark is the Whale Shark

– Filter feeder, feeds on plankton

Skeleton

• Sharks are cartilaginous fish

• Skeleton made of cartilage which is lighter and more flexible than bones

Respiration• Sharks have uncovered gills used for

respiration

• Extract oxygen as water passes over the gills

• Most species of shark can pump water over their gills for when they are not moving using the spiracle

• A small percentage of sharks need to stay in constant motion to respire

Teeth

• Sharks teeth are NOT attached to their jaws

• Teeth range from needlelike to large flat teeth

• Teeth are grown and replaced often

• Sharks have multiple rows of teeth

• Sharks can have about 25,000 to 30,000 teeth in one lifetime

• Some replace teeth every

8-10 days, others every few

months

Life Span• Lifespan varies by species

• Most live about 20 – 30 years

• The spiny dogfish can live up to 100 years

• It is thought that the whale shark can live over 100 years as well

Sense of Smell• Incredible sense of

smell

• They can detect amounts of blood as small as 1 ppm. (part per million)

• Rely on sense of smell to locate prey

Locating Prey

Electro-receptorsAllow sharks to

sense minute electricity caused by muscles and nerves in prey

Lateral linesSense organ used to detect motion or vibrations in the water

Vision

• Sharks have eyelids but do not blink

• Water surrounding eye cleans it

• Sharks have a membrane over eye that protects when being attacked or during predation

• Great White Sharks roll eyes back when attacking

Do Sharks Sleep??

• Scientists unsure!!

• Possible they sleep in a similar manner to Dolphins

– Half the brain sleeps at a time

Shark Attacks

• 2000 - 79 attacks, 11 fatalities

• 2005 - 61 attacks, 4 fatalities

• 2006 - 62 attacks, 4 fatalities

• Majority occur in the United States

• More people die from lightning strikes each year

Sharks Involved

• Three types of sharks have been involved in a significant amount of attacks– Great White– Tiger Shark– Bull Shark

Great White Shark• Great Whites are generally about 13-16 ft

and weigh 1500 - 2450 lbs

• Found in waters between 54 and 75 degrees F

• Countershading

– White underside and gray dorsal side

– Difficult to see when looking at horizontally

– When seen from above, gray blends in with the water

– When seen from below, white blends in with surface of water

Typical Prey• Sting rays, tuna, smaller sharks, dolphins,

seals, sea lions

• Shark attacks most often occur in the morning, within 2 hours after sunrise

• Hard to see a shark close to the bottom

• Attack from below at fast speeds

Tiger Sharks• Average 11 feet and 850 - 2000 lbs

• Commonly found around islands in the central Pacific

• Dark spots and stripes are prominent in young sharks and fade as the shark matures

Hunting Habits• Teeth can bite through

bone and turtle shells

• Known to circle its prey and even study it by prodding it with its snout

• Tiger sharks devour their entire prey when attacking

Hawaii

• Tiger sharks have become a problem in Hawaii

• Hunted to help control attacks, but no decrease occurred

• Considered sacred by native Hawaiians

Bull Shark

• Dwell in shallow water, possibly posing highest threat to humans

• Can tolerate freshwater

• Males: 6.8 ft, about 200 lbs

• Females: 11.5 ft, about 700 lbs

Hunting Habits

• Bump and Bite Technique

• Shark circles prey often bumping them before the actual attack.

• They are extremely territorial and will attack other animals that enter their territory.

Why attack?• Mistaken Identity:

– Shark mistakes a person in the water as a seal when looking from below the waters surface

• Curiosity

• Sharks typically bite once and then swim away

• Explanations:

– Humans do not taste like their typical prey

– Return to the prey after it exhausts itself

Dolphin Protection• Sharks will not attack

when dolphins are around

• Scientists unsure why this phenomenon occurs

Avoiding an Attack

• Avoid water during darkness or twilight hours

• Do not enter water if bleeding from an open wound

• Do not wear shiny jewelry – resembles fish scales

• Avoid areas near commercial fishing

• Avoid murky waters

• Do not splash a lot

Fending off an attack

• Hit back in sensitive areas such as the eyes and gills

• Shows shark you are not defenseless

Hammerhead Shark• Habitat: Shallow tropical and warm temperature waters

• Diet: Stingrays, Other small sharks, fish, crustaceans

• Size: 12 - 20 ft.

• Attacks: 18 (0 fatal)

• Hammerheads have small mouths and seem to do a lot of bottom-hunting. (Stingrays!)

• Their wide-set eyes give them a better visual range than most other sharks.

• They are also known to form schools during the day, sometimes in groups of over 100.